With the proliferation of new standards and applications for next generations of wireless communications, there has been a revolution in traditional integrated circuit (IC) design issues. Instead of designing an individual radio for each of the multiple standards and applications, a more cost-efficient solution would be to design multi-band radios that are capable of reusing blocks and area-consuming passive components for different standards and applications.
A critical block in radios that would greatly benefit from reusing passive components for different standards is the low noise amplifier (LNA), because of its extensive use of area-consuming inductors (or transformers) to achieve low noise, input matching, high gain, high selectivity, and high linearity.
There have been prior works that implement multi-band low noise amplifiers (LNAs). However, such works have their drawbacks.
For instance, in the work of Hashemi et al., “Concurrent multi-band low-noise amplifiers—theory, design, and applications,” IEEE J. Solid-State Circuits, vol. 50, No. 1, pp. 228-301, January 2002., higher order LC filters for input matching and for the output load are used in order to realize a concurrent dual band LNA. A drawback of this topology is that spurs in one band can corrupt the signal in the other band.
Quintal et al., “A Dual-band CMOS front-end with two gain modes for wireless LAN applications,” IEEE J. Solid-State Circuits, vol. 39, No. 11, pp. 2069-2073, November 2004, uses two common source, inductively degenerated input transistors with a shared source inductor. This topology requires fairly large gate inductors to resonate at the narrow bands of interest. Furthermore, the use of switches to tune out inductors in the load degrades the Q of the tank due to the switch on-resistance and its large parasitic capacitance.
In Hyvonen et al., “An ESD-protected, 2.45/5.25 GHz dual band CMOS LNA with series LC loads and a 0.5-V supply,” in IEEE RFIC Symp. Dig., 2005, pp. 43-46, series LC loads provide two separate outputs for each desired frequency, and allows the use of a lower supply voltage due to the use of series resonance. However, this topology uses six inductors, resulting in an increase in chip area.
Another drawback of the previous works discussed above is that they reuse inductors only for two different narrowband frequencies.
Magnusson et al., “An A 1.8-V wide-band CMOS LNA for multi-band multistandard front-end receiver,” in IEEE Euro. Solid State Conf. Dig., 2003, pp. 141-144, attains wideband, multi-band matching by using resistors at the expense of lower gain due to resistive feedback, worse noise figure, and lower voltage headroom. L. H. Lu et al., “A compact 2.4/5.2-GHz CMOS dual-band low-noise amplifier,” in IEEE Micro. And Wireless Comp. Letters, vol. 15, No. 10, pp. 685-687, October 2005, realizes dual-narrow band operation by switching in an additional transistor; however, using switches at the input degrades noise figure.